Tension controlling means for traveling offset webs



W W J Q mm May 19, 1931.

H. M BARBER TENSION CONTROLLING MEANS FOR TRAVELING OFFSET WEBS Filed Jan. 2, 1 930 haw WW MN H lNVENTOR WM 7%,, d E

ATTORNEYS BYv Patented May 19, 1931 nowann M. BARBER, or rawoA'rUe ,connnorrour, AssreNon wo o B. oor'rnntic 8;

sons ooMraNY, or wEsrEn-L manna rsrerm, a-cenronarron or DELAWARE TENSION comma-creme sin-ans son relive-Line orrsErwEBs Application .filed January 2, 1930. Serial No. $17,398.

In multicolor web perfecting presses where a traveling offset -web is'led around the 1mpression cylinder of the second printing unit under the printed web, it has been difficult to obtain clean and sharp printing.

I have discovered that if the tensionon the offset web necessary to the proper rewinding thereof be eliminated where the oil'- set web is in contact with the impression cyl-' inder of the second printing unit,thusper-- mitting the ofiset and printed webs to travel together around the impression cylinder, clean and sharp printing will be obtained.

To accomplish thisI provide the following means located between the second printing unitand the offset web rewindingmeeh- .anism;- i

2 First, a guide roller for ta-kingthe'offset web away from the impression cylinder under the same tension as'the printed web;

second, a compensatingdevice for the 011-- set web; and third, an offset web tension controlling mechanism through which'the oilset web is passed and given sufiicient" tension to 5 produce a perfect roll in the rewinding mechanism.

In practice, the travel of the printed web per cylinder revolution varies with the different forms used on the form cylinders,

thus making it next to impossible to properly proportion the guide rollersofthe otiset web tension controlling mechanism so that they will travel with the oliset web under all conditions. It is to prevent this variation from disturbing the offset web that I inter-pose aco nipensating device between the positiveeriven roller for taking thefoffset Web away from the impression cylinder and the offset web tension controlling mechanism.

' As it is quite difiicult to proportion the guide rollers ofthe offset web tension controlling mechanism so that they will feed the oilset web to the rewinding mechanism withr in the range of the compensating device, avariable speed'drive is employed for the offset web tension controlling mechanism.

A practical embodiment of my invention is represented in the accompanying drawings, in which Fig. 1 represents a'diagrammatic side elevation of that portion ofa multi color web perfecting printing press which. embodies my lnvention; and

Fig. 2 represents a detail'top plan view, showing the variable speed drive unit for the offset web tension controlling mechanism.

The form and impression cylinders of the second printing unit are denoted by '1, 2, 3-, 4, 5. The traveling printed web is'denoted by'6 and the traveling ofi'set web by 7,which offset web is shown as leading from thesupply roll 8 around the impression cylinder 5 to the take-up roll 9 of the offset web rewind ing mechanism." This rewinding mechanism, in the present instance, is shown as comprising a pair of rollers 10, 11, driven'from the gear 12 on the shaftof the impression cylinder 5' through the train of gears 13, 1 1, 15, 1-6, 17, 18, 19, 20, 21. i

The ofiset web tension controlling mechanism is shown herein as comprising a plurality of guide rollers 22, 23, 24:, around which the offset web is passed on its way from thesecond printing unit to the rewinding mechanism. These guide rollers are connected through gears 25, 26, 27.

A variable speed drive of any well known or approved form is provided for driving the web guide rollers 22, 23, 24 of the offset web tension mechanism, the one representedherein being the well known Reeves drive in which the shaft28 is, driven at a constant speed by the meshing of its gear 29 with the gear 19 of the train of gears leading'from the second printing unit to the offset web rewinding mechanism. The shiftable cone pulleys 30 on the constant speed shaft28 drive the shiftable cone pulleys 31 on the shaft 32 which is coupled to the shaft of the roller 22 of the offset web tension controlling mechanism, through the usual belt 33. The manually operated means for varying the speed of the shaft 32 is denoted as a whole by 34. 1 I

'The printed web-and the ofiset web'are taken ofi from the impression cylinder .5 at the same tension by providing theprinted' web guide roller and the offset web guide roller 36. The guide roller 35is driven from the gear 15 through the gear. gland theguide roller 36 is driven from the gear through V offset web tension controlling mechanism is V slow, theoffset web is threaded with a slight slack with the compensating roller 41 occupying the position shown in fulllines thereby allowing the roller to maintain its pressure on the web as the slack increases. If the travel ofthe said rollers 22, 23, 24 of the offset web tension controlling mechanism is fast, the offset web is threaded with a considerable slack with the compensating roller occupying the position shown in dotted lines thereby allowing the roller to maintain its pressure on the Web as the slack decreases.

As it is quite difficultto proportion the rollers 22, 23, 24 of. the offset web tension controlling mechanism so that they will feed the. offset web to the rewinding mechanism within the range of the compensating roller 41 it is desirable to use the va 'iable speed drive unit for the said rollers. As has hereinbefore been explained, the; constant speed shaft 28 of the variable speed drive unit is driven from the gear. 19 while the variable speed shaft 32 of said unit'is coupled to the shaft of the roller 22 of the offset web tension controlling mechanism. By the use of this variable speed drive it is not necessary to hold the diameters of the rollers 22, 23, 24 to such a close limit as when they are driven directly from the train of gears which connects the second printing unit with the offset web rewinding mechanism. Byv the use of this variable speed drive excess slack in the web between the rollers 36 and 22 can be removed by manually increasing the speed of the rollers 22, 23 and 24 or if any undue tension develops in the web at this point it can be eliminated bydnanually decreasing the speed of the said rollers. It is, of course, to'be understood that the rewinding mechanism is geared to rewind the offset web at whatever speed it is fed to them by the web tension controlling mechanism.

The above described arrangement causes the oflset and printed webs te travel together around the impression cylinder and thereby ensures clean and sharp printing on the printed web. 7 I

It' is evident that various changes-may be resorted to in the construction, formand arrangement of the several parts without departing'from the spirit and-scope of my invention; hence, I do not intend tohe limited to the particular embodiment herein shown and described,'but I i. I

What' I claim is r 1. In a multicolor web perfecting printing press, a printing unit, a traveling offset web, an offset web rewinding mechanism, a web tension controlling mechanism therefor, a variable speed drive for the web tension con trolling mechanism, and a web compensating device located between the printing unit and web, tension controlling mechanism.

2. In a multicolor web perfecting printing press, aweb printing unit, a traveling offset web, an offset web rewinding mechanism, means for taking the offset web away from the printing unit under the same tension as the web printed thereby, an offset web tension controlling mechanism for the rewindingv mechanism, and a variable speed drive for the web tension: controlling mechanism.

3. In a multicolor web perfecting printing press, a web printing unit, a traveling offset web, an offset web rewinding mechanism, means for taking the offset web away from the printing unit underthe same tension as the web printed thereby, an offset web'tension controllingmechanism for therewinding mechanism, a variable speed drive for the web tension controlling mechanism, and an offset web compensating device located be tween the printing unit and the offset web tension controlling mechanism.

4. In a multicolor web perfecting printing press, a printing unit, a traveling offsetweb,

on offset web rewinding mechanism,a train of gears connecting the printing unit ,and

rewindingmechanism, a web tension controlling mechanism for the rewinding mechanism, and a variable speed drive unit con-' necting said train of gears with the web tension controlling mechanism.

5. In a multicolor web perfecting printing press, a printing unit, a traveling offset web; on offset web rewinding mechanism, a train of gears connecting the printing unit and rewinding mechanism, a web tension controlling mechanism for he rewinding mechanism, a variable speed drive unit connecting said train of gears with the web tension controlling mechanism, and an offset web commy invention, I have signed my name this 30th day of December, 1929. V

HOWARD M. BARBER. 

